I have a B.S. in Nutritional Science and Toxicology and a M.S. in Human Nutrition. It has come in very handy on both the wards and in the clinic. Not many physicians have a strong knowledge-base when it comes to the data behind nutrition. All in all, I've been very glad about my major. I'm planning on going into Gastroenterology, where my background will come in very handy at times.
I'm not an osteopathic student, but nutrition fits in with healthcare period.